A disk drive comprises a rotating disk and a head over the disk to magnetically write to and read data from the disk. The head may be connected to a distal end of an actuator arm that is rotated about a pivot to position the head radially over the disk. The disk may comprise a plurality of radially spaced, concentric tracks for recording data and servo information on the disk. The servo information may be read by the head to generate a position error signal (PES) indicating the deviation of the head position from a desired track. The PES may be fed to a track follow controller that adjusts the head position in a direction that reduces the PES to keep the head on the desired track.
Disturbances, such as vibrations, are becoming an increasing problem for disk drives. As the data area density of the disk continues to increase, the tracks per inch (TPI) becomes higher, making it more difficult for the track follow controller to keep the head on track under disturbance conditions. Also, in many mobile devices, the disk drive is mounted near speakers, which generate audio vibrations that can propagate to the disk drive and impact disk performance.
Accordingly, there is a need for adaptive track follow control that is able to provide good track follow performance under different disturbance conditions.